A crawler device including front and rear wheels and a crawler belt wrapped around the wheels is well known in the art.
For example, in a crawler device to be put under a relatively light load such as a one used in a robot, torque may be transmitted via friction between an inner periphery of a crawler belt and an outer periphery of a wheel or may be transmitted by engagement of engagement portions formed in the outer periphery of the wheel and engagement portions formed in the crawler belt.
In such a crawler device, it is required to provide means for preventing the crawler belt from being disengaged from the wheel when the crawler belt is subjected to a force in a width direction.
In a crawler device disclosed in FIGS. 1 to 4 of Patent Document 1, plates are fixed to side plates disposed in opposite sides of a crawler belt. Disengagement of the crawler belt is prevented by the plates.
In a crawler device disclosed in FIG. 5 of Patent Document 1, a pair of endless ribs that extend inwardly in a radial direction and are continuous in a peripheral direction are respectively formed in opposite side edges of a crawler belt. Disengagement of the crawler belt is prevented by engagement of the pair of ribs with opposite side surfaces of a wheel.
A crawler device disclosed in Patent Document 2 includes features similar to those of Patent Document 1 although these features are not provided for the purpose of preventing disengagement of a crawler belt. Specifically, a pair of ribs that extend inwardly in a radial direction and are continuous in a peripheral direction are formed in opposite side edges of the crawler belt. The ribs are engageable with side plates that support a wheel.